There are many and varied articles appearing in this medium that give an inaccurate explanation about lock bumping. Having read through many similar articles here, attempting to impart the facts about the phenomena, I cant help but feel that all these “so called” experts actually have no idea what they are talking about. Lock bumping has been known and in existence prior to the invention of the modern pin tumbler principle by Linus Yale Jr in 1862.
The original design of the pin tumbler method was found in ancient Egypt, where actual working models of a wooden pin tumbler lock were found during excavations of ancient sites. One of the oldest of these locks is on display at Israel’s museum that houses the original Dead Sea Scrolls. The modern Yale type key cylinder indeed uses two sets of pin tumblers combined with springs and a “warded” keyway to establish a perceived secure locking mechanism.
Lock bumping focuses on the ability to recreate the “shear” line, normally created by the original correct key for the cylinder, by use of a key of the same ward design as the target cylinder, but modified to the maximum depth for each tumbler position (the cuts on the key).
The bump key is inserted into said keyway, partially. The head of the key is tapped with a hammer or screwdriver, while exerting minimal twisting pressure on the key. The action produces enough kinetic energy to “bump” the pin tumblers inside the chambers to recreate the “shear line”.
Whereas, previous authors suggest that the method was discovered by locksmiths in Denmark in the 1970’s, the truth is that virtually all locksmiths have known about the bypass FOREVER! The primary reason that lock bumping had been kept quiet and within the trade, was to protect the marketplace from the potential feeling of insecurity that the knowledge could bring.
Only since the advent of the internet, has the phenomena spread like a virus onto the scene. There are a few manufacturers that have reacted to this hype and produced their own versions of “bump resistant” locks, but most of their attempts have not created 100% guaranteed bump proof products. There are already two 100% fully guaranteed bump proof (and virtually pick proof) key cylinder types available today. Abloy and Bilock. Abloy is of Finnish design and has been around since 1908, while Bilock is an Australian design that has been around since 1972.
Contrary to the beliefs of some of the previous authors, these bump proof locks are not “that” expensive and are aesthetically pleasing and readily available all over the world. Truth be told, the instances of lock bumping are almost impossible to detect due to the action being representative of using a key. If you wish to find out methods and products that will prevent this method of attack, contact the author.